Methods for the preparation of aliphatic alcohols having from 1 to 5 carbon atoms from the corresponding olefins are well known. Broadly, an enriched olefin feedstream is reacted in the presence of an acidic reacting catalyst at an elevated temperature to produce the reaction product containing a saturated aliphatic alcohol. In the direct hydration process, an olefin feedstream and water are contacted with a solid catalyst having acidic reaction sites to produce an aqueous reaction product containing the product alcohol.
During the synthesis of alcohols by acidic hydration of olefins, the corresponding ether is also formed as an undesired by-product. It is known that the formation of ether can be repressed by recycling the ethers distilled off from the alcohols. If the formation of ether is completely suppressed by recycling the ether to the feedstock charged to the reactor, significant disadvantages are encountered. For instance, we have found in test runs that the space/time yield e.g. in the IPA synthesis decreases by this measure by 30% to 50%, depending on the concentration of the propylene feedstock. Moreover, if large amounts of gas are recycled, i.e. if the gas conversion per pass is low, considerable quantities of ether have to be recycled. The additional vaporization of ether in the feedstock results in a higher energy consumption.
An alternative method is the separate splitting of ether by passing the vaporous ether over alumina, cf. Houben-Weyl, Methoden der Organischen Chemie (Methods of Organic Chemistry) VI 3 (1965), 143. However, by the reaction of diisopropyl ether mainly propene and only small amounts of alcohol are obtained. No process for the direct conversion of an aliphatic ether according to the equation EQU R--O--R'+H.sub.2 O.fwdarw.ROH+R'OH or EQU R--O--R+H.sub.2 O.fwdarw.2ROH,
wherein R and R' represent alkyl groups with 1 to 5 carbon atoms, is known.
It is the object of the present invention to make available a process allowing the direct and quantitative conversion of an ether into the corresponding alcohol thereby increasing the yield of the alcohol.